The official said three rockets were detected and the "Iron Dome" defensive missile system was activated.

An official said: "A few minutes ago, Palestinian terrorists in Gaza fired three rockets at Dimona. Two fell in open areas, Iron Dome intercepted the other."

The Ezzedine Al-Qassam Brigades, the military wing of Hamas, said it "launched three M75 rockets at Dimona". The rockets have a range of about 50 miles.

Israeli troops also killed two Gaza militants in a seafront gunfight on Wednesday, close to the site of a failed attack on a military base a day earlier, according to reports.

"Two armed terrorists came out of the sea more or less in the same area where the incident took place 24 hours ago," Israeli public radio said.

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Gallery: The Conflict In Gaza And Israel

Israel and Hamas continue to fire missiles at each other's territory. Here an Israeli airstrike on a suspected rocket launch site

"Army lookouts spotted them and there was a gunfight which ended with both terrorists killed."

In response to the escalating conflict, sources said the United Nations Security Council would convene in New York on Thursday at 10am local time.

It follows a call by Arab nations for an emergency meeting and immediate action to end what they say is Israel's "outrageous onslaught" against Palestinians.

Video:Wedding Guests Flee Rocket Attack

The nuclear reactor strike attempt comes after the Israeli military has said it has shot down rockets fired by Palestinian militants at other areas, as Israel's major air offensive over the Gaza Strip approaches its third day.

A spokesperson for the Israeli Defence Forces (IDF) said at least eight rockets sent from Gaza were intercepted over Tel Aviv, Ashdod and Ashkelon on Wednesday.

Israel said a rocket hit the city of Zichron Yaakov on Wednesday afternoon, which is some 120km (75 miles) from Gaza, representing the longest-range rocket strike by Hamas on the state to date.

Video:Israel's 'Iron Dome' Explained

The IDF claims at least 48 missiles, sent by Hamas, which controls Gaza, "struck Israel" since midnight.

Other locations targeted included Beersheva and Sderot in the south, Rishon Lezion, and Hadera in the north - 60 miles from Gaza.

In total, more than 300 rockets have been fired at Israel since the military launched Operation Protective Edge on Monday night.

Video:Palestinians Slate Israeli Tactics

To date no fatalities have been reported in Israel.

The fatalities come after at least 49 people, including children, have been killed in the biggest Israeli assault on Gaza in nearly two years.

Officials in Gaza say that more than 300 people have also been injured since Monday, but that number is likely to climb as Israel attempts to "dismantles" Hamas.

Video:Israel's 'Defensive' Strategic Goal

The Israeli military said a total of 550 Hamas targets have been hit since the operation began, with 130 targets hit on Wednesday.

They included 60 suspected rocket launch sites on the Gaza Strip from Beit Hanoun in the north, to Rafah near the Egyptian border.

Israeli Prime Minister Benjamin Netanyahu's office has quoted him as saying he plans to "intensify the attacks on Hamas and the terrorist organisations in Gaza" even further.

The Israeli cabinet has warned it may also send in ground troops and has authorised the call-up of as many as 40,000 reservists.

At a crisis meeting in the West Bank city of Ramallah, Palestinian President Mahmoud Abbas accused Israel of committing atrocities in Gaza.